18 personnel who were on board at the time of the incident are still feared to be trapped inside.
Officials say the submarine is largely submerged under water now and a large part of it has been gutted.
A major fire broke out on board the INS Sindhurakshak submarine at the Mumbai Naval Dockyard late on Tuesday night.
Officials say that an explosion caused the fire, but the cause of the explosion is not yet known.
At least 16 fire tenders were sent to the location apart from Navy's internal fire fighting team.